Grand Ayatollah Ali al-Sistani delivered his message Friday in a sermon read by a representative in the city of Najaf.

Several days of apparent reprisal attacks have followed a double suicide bombing Monday in the town of Muqdadiyah in Diyala province, about 60 miles (90 kilometers) north of Baghdad. The bombing, which targeted a cafe frequented by Shiite militiamen, was claimed by the Islamic State group.

Residents have since reported attacks on Sunni mosques and business. Two Iraqi journalists were killed near the provincial capital Tuesday.

Diyala province is historically mixed between Sunnis and Shiites, but Shiite militias handle most of the security since IS was pushed out in early 2015.